JPH0616454Y2 - Lightning arrester - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a lightning arrester using a non-linear resistor that suppresses an abnormal voltage such as a distribution line laid on a power pole or a power panel.

[Prior Art] Conventionally, in a distribution system such as a distribution line or a power panel and a power receiving circuit,
Many lightning arresters that use non-linear resistors, such as zinc oxide elements (sometimes called surge absorbers) are used, but zinc oxide elements absorb surge voltage generated in the system and suppress abnormal voltage. By performing the operation duty, the deterioration current gradually deteriorates, and the leakage current increases as the deterioration progresses.

In this way, even if there is a slight increase in the leakage current, the surge voltage absorption capacity does not drop significantly. However, if the leakage current increases, the temperature in the steady state rises, and if the temperature rises, the leakage current also increases and the temperature further rises. Therefore, when the element deteriorates, there is a risk of heat escape and thermal destruction. Therefore, it is necessary to detect and replace a deteriorated product before heat escape.

FIG. 2 is a block diagram showing a conventional surge absorber disclosed in, for example, Japanese Utility Model Laid-Open No. 60-88486. In the figure, (2
(1) is a zinc oxide element which is a non-linear resistor, (22) is an irreversible color change member attached around the zinc oxide element (21), (2)
3) is an electrode provided at both ends of the zinc oxide element (21), and (24) is a lead wire.

The surge absorber is used to absorb the surge voltage of the circuit such as the control panel. Even if it absorbs the abnormal voltage that normally occurs, the temperature does not rise much, but it gradually deteriorates as the number of surge duty increases. As a result, the leakage current increases and the surge voltage absorption capability also decreases. For this reason, it is necessary to renew it if it fulfills some responsibility.

When the leakage current of the zinc oxide element (21) increases, the temperature rises in a steady state, and there is a problem of heat escape as described above. On the other hand, the deterioration of the zinc oxide element (21) can be detected by examining the correlation between the temperature rise and the leakage current, setting the limit of the temperature rise due to the leakage current, and monitoring the temperature.

In the second configuration, since the irreversible color changing member (22) that changes color at a predetermined temperature adheres to the periphery of the zinc oxide element (21), the color change of the irreversible color changing member (22) causes the zinc oxide element (21). Can be detected.

[Problems to be Solved by the Invention] In the conventional surge absorber as described above, even a normal zinc oxide element (21) capable of absorbing surge voltage
When a surge voltage with large energy is absorbed, the temperature of the zinc oxide element (21) rises, so depending on the set temperature of the irreversible color change member (22), the zinc oxide element (21) does not deteriorate. Nevertheless, there was a problem that the irreversible color changing member (22) changed its color and could be erroneously detected as a deteriorated product.

This invention has been made in order to solve the above problems, and can prevent erroneous detection of deterioration due to temperature rise for only a short time when a nonlinear resistor absorbs a surge voltage, An object of the present invention is to provide a lightning arrester that can detect deterioration of a non-linear resistor more reliably.

[Means for Solving the Problems] In the lightning arrester according to the present invention, when the non-linear resistor that absorbs the surge voltage absorbs the surge voltage and the temperature temporarily rises, the irreversible color changing member changes color. Instead, the distance between the non-linear resistor and the irreversible color change member is maintained so that the color changes only when the zinc oxide element deteriorates and the leakage current increases, and a conductive heat absorbing member is provided between the two. The color change temperature of the irreversible color change member is set to a temperature at which heat does not escape.

[Operation] By arranging the heat absorbing member between the non-linear resistor and the irreversible color change member, even if the non-linear resistor temporarily rises in temperature by absorbing surge voltage during normal operation, The amount of heat generated by is absorbed by the heat absorbing member and the temperature of the part where the irreversible color changing member is attached is low, the irreversible color changing member does not change color, and the non-linear resistor deteriorates and leakage current increases, and However, when the temperature rises, it is possible to detect a deteriorated product due to the color change of the irreversible color change member.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, (1) is an porcelain tube, (2) is an upper lid as a sealing metal member fixed to the porcelain tube (1) via an O-ring (3), and is made of stainless steel or the like integrally with the line side terminal. Is formed by drawing the material. (4) is a porcelain tube (1)
A zinc oxide element as a non-linear resistor inserted in the
(5) is a coil spring for fixing the zinc oxide element (4),
(6) is a spacer that also serves as a storage case for the water adsorbent (7), (8) is a stopper for preventing lateral movement of the zinc oxide element (4), and (9) is the same as the upper lid (2). The lower lid as a sealing metal fitting having the structure and function, and (10) is a bracket for mounting the lightning arrester on a utility pole or the like.

(11) is an irreversible color changing member (hereinafter abbreviated as color changing member) such as a thermo label that changes color depending on the temperature used as a detection device, and is attached to the lower lid (9) so that it can be easily seen from under current, for example. Has been done. (12) is a metal block such as aluminum or copper having a large heat capacity and good heat conductivity, which is used as the heat absorbing member.

Next, the operation will be described.

The maximum temperature transmitted to the color changing member (11) when the temperature of the zinc oxide element (4) temporarily rises due to the surge can be calculated as follows.

Here, Δt ₁ : Temperature rise value of zinc oxide element during surge treatment Δt ₂ : Temperature rise value of discoloration member (11) M ₁ : Heat capacity of zinc oxide element M ₂ : Heat capacity of metal block That is, metal block ( If the heat capacity M _{2 of} 12) is increased, the temperature t ₂ of the color changing member (11) can be suppressed.

On the other hand, the steady temperature of the zinc oxide element (4) due to the resistance leakage current is transmitted to the color changing member (11) as follows.

First, the calorific value per unit time of the zinc oxide element (4) is Q
Then, the following equation holds.

Here, t ₀ : atmospheric temperature t ₁ : steady temperature of zinc oxide element t ₂ : temperature of discoloring member A ₀ : area radiating heat to the atmosphere A ₂ : area where heat of metal block flows ₂ : heat of metal block Flow length λ: Thermal conductivity of metal block α: Heat transfer coefficient to the atmosphere From equation (2), the temperature t ₂ of the color change member (11) is given by the following equation.

The above theory is applied to a surge arrester for distribution with a system voltage of 6.6 kV, for example. First, the heat capacity M ₁ of the zinc oxide element (4)
Is calculated by the following equation.

M ₁ = c ₁ ρ ₂ × π / 4d ₁ ² × ₁ (4) where c _{1 is} the specific heat of the zinc oxide element, 0.125 cal / g ° C. ρ ₁ : the density of the zinc oxide element, 5.4 g / cm ³ d ₁ : Diameter of zinc oxide element, d ₁ cm ₁ : Height, ₁ cm M ₁ = 0.125 × 5.4 × π / 4 × d ₁ ² × ₁ = 0.53d ₁ ²
_If an aluminum material having the same diameter and the same heat capacity as the zinc oxide element is adopted as the metal block ( ₁ cal / ° C.), the height ₂ can be obtained by the following equation, where the heat capacity of the aluminum material is M ₂ .

M ₂ = M ₁ M ₂ = c ₂ ρ ₂ × π / 4 × d ₂ ² × ₂ (5) where c ₂ : specific heat of aluminum block 0.214 cal / g ° C ρ ₂ : density of aluminum block 2.71 g / cm ³ d ₂ : Aluminum block diameter d ₂ cm ₂ : Height ₂ cm That is, the height of the aluminum block (12) having the same diameter and the same heat capacity as the zinc oxide element (4) is 1.16 times the element height.

When the surge voltage of the zinc oxide element (4) is absorbed, the temperature rise value Δt ₁ is about 20 deg.
The temperature rise value Δt ₂ transmitted to the color change member (11) is M ₁ = M
_{When it is 2} , from equation (1) Next, when the zinc oxide element (4) deteriorates and its temperature constantly rises by 10 deg from the maximum atmospheric temperature of 40 ° C., the temperature t ₂ of the portion to which the color changing member (11) is attached is Consider using equation (3).

t ₀ : Maximum temperature of the atmosphere 40 ° C. t ₁ : Steady maximum temperature of the zinc oxide element 50 ° C. A ₀ : Area radiating heat to the atmosphere (considering the insulator surface area and other parts, it is about 10 times A ₂ ) 10A ₂ cm ² A ₂ : Cross-sectional area of aluminum block A ₂ cm ² λ: 〃 Thermal conductivity 0.486 cal / cm · sec ・ ℃ ₂ : Height of aluminum block ₂ cm α: Thermal conductivity to atmosphere 10 ^-4 cal / cm ²・ sec ・ ° C I.e. Here, assuming that the height ₁ of the zinc oxide element (4) is 5 cm, the height ₂ of the aluminum block (12) having the same heat capacity as the zinc oxide element (4) is 5.8 cm according to the equation (6). .

Therefore, the temperature t ₂ of the color change member (11) can be calculated from the equation (7). Becomes

Furthermore, assuming that the height ₁ of the zinc oxide element (4) is 10 cm, t ₂ is the same as above. Becomes

The height of the zinc oxide element (4) is 10 cm, the system voltage is 11
It corresponds to the lightning arrester used for kV system.

That is, when the deterioration progresses, the zinc oxide element (4)
It can be considered that the temperature of is directly transmitted to the color change member (11).

From the above examination, considering the maximum atmospheric temperature as 40 ° C and setting the color changing temperature of the color changing member (11) at 50 ° C or higher,
The discoloring member (11) does not discolor due to the surge absorption, and discolors when the leakage current increases.

However, without the aluminum block (12),
The color changing temperature of the color changing member (11) must be set to 60 ° C. or higher, and the sensitivity of deterioration detection is deteriorated by 10 ° C.

From the above, the temperature to be detected when the zinc oxide element (4) deteriorates and rises in temperature in a steady state is
The temperature of the part where the discoloration member (11) adheres when the temperature of the zinc oxide element (4) absorbs surge voltage and rises temporarily when the balance between heat generation and heat dissipation is lost and becomes lower than the heat escape temperature. The heat capacity of the metal block (12) may be set so as to be lower than the above set temperature. Considering this condition and practicality in terms of operation, the heat capacity including the storage case of the moisture adsorbent (7), the spacer (6) and the like and the metal block (12) which compose the lightning arrester is determined by the zinc oxide element (4). It is realistic to make it equal to or more than the heat capacity of).

In the above embodiment, the metal block (1
2) In particular, an aluminum block was used, but the present invention is not limited to this, and it is obvious that other metals such as copper, true chew, stainless steel, etc., or materials other than metal may be used. What is important is that the material has good thermal conductivity and has a volume having an appropriate heat capacity for absorbing heat generated by surge treatment.

In the above calculation, only the aluminum block (12) absorbs heat, but in reality, the lower lid (9), stopper (8), spacer (6), etc. of FIG. Therefore, the temperature at the time of surge voltage absorption becomes even lower. Further, even if the stopper (8) is made thicker and brought into close contact with the zinc oxide element (4) so as to be thermally bonded thereto, the same effect can be obtained even if they are dispersed and arranged.

Although the zinc oxide element (4) is used as the non-linear resistor, other metal oxide type element may be used.

By the way, in the above description, the case where the present invention is applied to the lightning arrester for electric power distribution has been described, but the same effect can be obtained even if the lightning arrester is used for other purposes.

[Effects of the Invention] As described above, the arrester of the present invention has a non-linear resistor,
Since a heat absorbing member that absorbs the temporary heat generated by the absorption of the surge voltage is provided by being thermally coupled, it does not respond to the temporary heat generated by the non-linear resistor due to the surge, and the non-linear resistance caused by the resistance leakage current. The steady temperature rise of the body can be detected with high sensitivity to detect the deteriorated product more reliably and easily, and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a lightning arrester according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a case of a surge absorber as a conventional example. (4) is a zinc oxide element as a non-linear resistor element, (11)
Is an irreversible color change member as a detection device, and (12) is a metal block as a heat absorbing member.

Claims (3)

[Scope of utility model registration request] 1. A porcelain insulator whose both ends are sealed with sealing metal fittings, a non-linear resistor which is inserted into an inner diameter portion of the porcelain insulator and absorbs a surge voltage, and which absorbs heat generated by the non-linear resistor and the non-linear resistor. A heat absorbing member for thermally and electrically connecting the body and the sealing metal fitting at one end, and an irreversible color change member attached to the outer surface of the sealing metal fitting at the one end. Lightning arrester. 2. The lightning arrester according to claim 1, wherein the heat absorbing member has a heat capacity of at least the heat capacity of the non-linear resistor. 3. The utility model registration claim 1 in which the heat absorbing members are dispersedly arranged between the lower portion and the upper portion of the non-linear resistor or between the lower portion and the upper portion and the non-linear resistor. Alternatively, the arrester according to item 2.